Wedge-action lock washers are useful because they tend to become tighter under vibration. Examples of such wedge-action locking devices are disclosed in U.S. Pat. No. 3,263,727 which was issued Aug. 2, 1966 to Arthur B. Herpolsheimer; U.S. Pat. No. 3,417,802 which was issued Dec. 24, 1968 to Carl O. Oldenkott; and U.S. Pat. No. 5,080,505 which was issued Jan. 14, 1992 to Allstair N. McKinlay.
Identically-shaped washers are supplied to the user in individual components which he then must install with the cam faces in a face-to-face relationship. Should one or both of the washers be reversed, the device will not function when a bolt is tightened on the workpiece. It loses its self-locking function.
U.S. Pat. No. 4,538,313 which was issued Sep. 3, 1985 to Bent O. Frieberg suggested one solution to the accidental or careless reversal of the washer faces in the form of bonding material, such as a glue or an adhesive applied to the two washers to keep them coupled until such time as a rotational force is applied during the tightening of a fastening device.